PITTSBURGH, April 1 (UPI) — In the first study of its kind in 30 years, scientists say they have documented industry’s use of water resources in the United States.

Carnegie Mellon University Professor Chris Hendrickson and colleagues said industry, including agriculture, has long been recognized as the biggest consumer of water in the United States. However, estimates of water consumption on an industry-by-industry basis are incomplete and outdated, with the last figures from the U.S. Census Bureau dating to 1982.

The scientists said they estimated water use among more than 400 industrial sectors and discovered most water use occurs indirectly as a result of processing, such as packaging and shipping food crops to the supermarket, rather than direct use, such as watering crops.

Among the findings for consumer products: It takes 200 gallons of water to make $1 worth of dog or cat food, 270 gallons to place $1 worth of sugar on store shelves and 140 gallons of water to make $1 worth of milk.

“The study gives a way to look at how we might use water more efficiently and allows us to hone in on the sectors that use the most water so we can start generating ideas and technologies for better management,” the scientists said.

The research is published in the American Chemical Society journal Environmental Science & Technology.